Hydroplane-boat.



G. A. CROCCO.

HYDHOPLANE BOAT.

APPLICATION HLED APR.1o.19o.

Patented June 13, 1916,

GAETANO .ARTURO CROCCO,r 0F ROME, ITALY.

HYDROPLANE-IBOAT.

Specification of Letters Patent.

Application filed April 10, 1908. Serial No. 426,269.

To all whom it may concern.' V

Be it `known that I., GAETANO ARTURO Cnoeco, a subject of the King ofItaly, re-

siding at Rome,`Italy, have invented a new 'and useful Improvement in Hydroplane- Boats; and I do hereby declare the following to be a full, clear, andexact description of the same.

Now the present invention relates to certain improvements in the arrangement of.

the fins or blades of the hydroplane boats, the object of which is to secure a greater stability in the first phase of the run, viz: when the body of the boat is gradually emerging from the water, at the same time considerably reducing the number of the lins as well as their size.

In the annexed drawings which show how said invention can be carried into practice: Figure l showsahydroplane boat in the first phase of the run, the stem of which has emerged from the water, while the lbottom at the stern still remains in contact with the Water. Figs. 2 and 3 are two transverse sections of the same boat and to each of them the form of the blade is added. Fig. 4 shows the same boat while in motion, when the body has emerged from the water. Figs. 5

'and 6 are both side elevations of another form of hydroplane boat according to the present' invention, in two dierent phases ofthe run.

In a`ll the hydroplane boats heretofore lmown it is necessary, in order to insure a suflcientstability, 'to reduce gradually the surface ofthe supporting fins while the speed is increasing, in order tokeep the stability always constant. In order to insure a perfect stability it is necessary in all the hydroplane boats, as soon as the vertical thrust of the fins has reached the value of the weight ofthe boat, tol keep said thrust constanty irrespective of any further variation of theV speed above the normal limit.

. speed 'becomes higher and the verticall thrust remains constant@ Both arrangements are l objectionable; the arrangement of the movable fins because it introduces hinges and other articulations which are liable to give trouble and get out of order; the arrangement of the superposed fins because the construction of the boat becomes much more complicated. Apparently those hydroplane boats having V-shaped fins should be `free from said objection, because the supporting.

surface ofthe fins diminishes automatically as the boat is raised and by conveniently shaping the fins a perfect regulation should be obtained. lhis automatical reguistiou by means of V-shaped is prevented in practice by serieus structural diiculties. f

Fig. '2 shows clearly where the diiiiculty lies; the undulated line b indicates the level of the water whenthe hydroplane is at resti y Patented aan@ is, raie.'

and the line mfthe same level when the hydroplane is running at its normal speed.

The reference characters-arindicates the fins and the portion in full lines. corresponds to the fins of a hydroplane boat in accordance with the present invention2 while said p ortion'in full lines together wlth the portion shown in dotted lines shows the size which the fins had to .attain if the diminution of the supporting surface should begin directly with the lifting of the boat. It will be understood that many difiiculties had tobe overcome for stiii'ening conveniently fins having such a considerable length and the weight of the boat would be also increased and more room would be required in performing any movement.

The object of the present invention is-a novel arrangement of the fins, permitting an easy lifting of the beat above the water, keeping at the same time a perfect stability without using superposed fins or in the case of V-shaped fins, Without giving them an excessive length. This result is obtained by a particular distribution of the supporting surfaces of the fins, which distribution is a departure from the practice hitherto in general use for this class of boats.

Heretofore the supporting surfaces` have been arranged in such a manner that the resultant of the vertical thrusts on the various groups of fins coincided with the vertical line passing through the center of gravity of the boat, and therefore the boat was lifted while keeping same on an even keel or nearly so. Now in accordance with the presentinlvention the supporting surfaces are distrib uted in such a manner that the resultant of the vertical thrusts on the various groups of4 the movement, differing from the inclination fins lies forward ofthe vertical line passing through Vthe center of gravity'when the lboat is at rest. or when the hull has not all emerged from the water. It ensues that the boat is lifted in this case in two successive steps, that .is in a first period the bow rises and thetransversal stability, until the fore fins reach,the surface, is secured by the bottom of the boat skimming above the water at the stern; in a second period the stern portion of the boat rises gradually and is ,lifted clear from the water'. At this moment the .boat increases lher speed` to the maximum and bothy the groups of vfins or only a group, if desired, help to the stability of the boat.

The practical execution of .this arrangement requires firstly a liatvery. stable astern and for this purpose-the usual racing boats having a finely cut and deep bow and flat bottomed stern are well suited. The same results can be secured, however, also by means of boats of the old pattern providing same with steadying surfaces astern. The

fiat bottomed boats have the further advan tage ofhelping'with their bottom in lifting the stern during the second period.

Secondly it should be remarked that the fins at the end of the first period have an inclination with respect to the direction of they have at the beginning of the period, because the axis of the boat takes an inclined position. This particular movement is of the greatest' importance, because it allows the reduction of the supporting surfaces and further renders possible tarrangejsame in. such a manner that while-at the beginning of the run the lifting ofthe. stern follows the lifting of the bow, at the end of the run it is the lowering of the stern that precedes the lowering of the bow. This condition' is indispensable for the safety and stabilityr o f the system.

.Thirdly the surface of the fins ought to be distributed in such a manner that the fore fins support for a given angle corresponding to the horizontal position of the boat their share of load at a lower lspeed than that required by the fins at the stern.

In. the practicalv form of execution shown in the drawings -d- (Figs. 1 and 4 .des-V ignates the stern, -ethe bow of the boat having aflat bottom stern as shown in Fig. 2. The fins w.-cv'c\`-care secured to the boat by means of braced struts -f-g-.

The aft fins aa- Fig. 2, in thel form of boat illustrated are arranged in the shape of a V without vertex, while the fore fins -c-c- (Fig. 3) are in the -shapeof a complete V. This arrangement has given in practice excellent results, but nothing prevents adopting for the fore fins the same shape as for the fins at the stern. It is also possible to adopt for both groups of fins the form shown in Fig. 3, but in\this case, when l the boat is going at full speed it is lifted clear convenient curve.

It should be remarked that by having-at the stern'the fins in the shape of a V without vertex,'there Yremains between the lower ends.

of the fins a free space in which can be" 'Fi 2. The form of construction hereinf:

be ore described shows only 'a particular instance of the mode of carrying the invention into practice, because the system of raising the boat in.. two different times canv be ad# vantageously employed1 not 'onlyA in the hydroplane boats with V-shaped fins, but also in the hydroplane boats with horizontal fins (in the transverse direction) of either' the simple or'of the multiple type. In this case the vmethod lforming the object of the present invention allows the reduction of the number of fins 'and makes it possible'toarrange f them Aat a great depth underthe'hull, without 'impairing the stability of the boat.

. Figs. 5and6 show by way of example the invention as applied to a boat with horizontal fins. To the hull -pthe fins `4]- z'-s are secured by means of suitable supports. Fig.'5 represents the 'boat at the-endv of the first time: Fig.- 6 the-boat at the end of the second time lifted clear above the water surface It will be seen that the fins are arranged at the stern in a single.

gane and at bow at two diiferentheights. owev'er fins all at the same height or at various heights, even more than two, may

be adopted also ,on the bow ;.and at the stern also a multiple system of fins.

I claim:

1.- In hydroplaneboats vthe combination of a' boat with avi-lat bottomed stern, a group of V-shaped fins at thev bow and a group of ins'in the shape of an incomplete V at the 'i stern, as shown and for lthe purposes. set forth. i 2. In hydroplane boats the combination of a group. of fins at the bow having the shape of a complete V, a group at the stern i having the shape of a V with the vertex cut off,` a rudder and a propeller placed in the free space inclosedv between thetwo fins at the stern or in the direction of same.

3. In hydroplane boats of the class in which the extension of the submerged supporting surface is progressively reduced while the boat is progressively emerging thrust of the bow fins, by the submerged sur` face of said bow fins multiplied by their mean unitary thrust is greater than the product of the distance between the center of gravity of the boat andthe resultant of the vertical thrust of the stern, by the 'submerged surface of said stern ns multiplied by their mean unitary vertical thrust, for the purpose set forth.

4. In hydroplane boats of the class in which the extension of the submerged supporting surfaces is progressively reduced while the boat is progressively emerging from the Water, supporting fins provided at the bow and at the stern of the boat, ar-

ranged in such a manner that in any position of the boat from the'position she takes before she has reached the normal run above the water to the position with her bottom skimming astern at the surface of the water and the bow raised above the water in the position it takes in the normal run the product of the distance 'between the center of gravity of the boat and the resultant of the vertical thrust of the submerged portion of the bow ins, by the surface of said submerged portion of the bow tins multiplied by their mean unitary vertical thrust, is smaller than the product of the distance between the center of gravity of the boat and the resultant of thevvertical thrust of the submerged portion of the stern fins, by the surface of said submerged portion of the stern fins multiplied by their mean vertical unitary thrust, for the purposes set forth.

In testimony'whereof7 I have signed my 

